1. Field of the Invention
The present invention relates to a TTL automatic light controlling camera system, a camera body and a flashing device, the TTL automatic light controlling camera system being constituted by combining a camera body and a flashing device.
2. Related Background Art
Hitherto, camera systems capable of controlling light by a TTL method have been arranged in such a manner that one light receiving element is included in the camera body at a position at which it confronts the entire surface or an essential portion of a film. Furthermore, a shutter disposed between the film surface and the light receiving element is completely opened before a flashing device commences to emit light. Light of the subject field reflected from the surface of the film is photoelectrically converted by the light receiving element. Then, a signal corresponding to the quantity of the integrated quantity of light is subjected to a comparison with a predetermined value. As a result, the quantity of light emitted from the flashing device is controlled so as to obtain a predetermined brightness on the surface of the film. However, the above-described system cannot satisfactorily control light in various states of the subject field because the region of the subject field which can be detected is a one-dimensional region. Therefore, a problem arises in that exposure of the essential subject field desired by the photographer cannot be obtained. Accordingly, various structures have been developed recently for the purpose of overcoming the above-described problems.
For example, a system has been disclosed in U.S. Ser. No. 560,745 in which the idea of a so-called multi-pattern photometry is adapted to the TTL automatic light control system. According to this disclosure, a plurality of photoelectrically converting means capable of measuring light of the subject field by dividing the field into a plurality of regions are disposed to confront the surface of a film. Furthermore, the flashing device is caused to pre-emit (previously emit) light immediately before a focal plane shutter disposed between the surface of the film and the plurality of the photoelectrically converting means is opened. The plurality of the photoelectrically converting means receive light of the subject image due to the previous light emission and reflected by the surface of the shutter. The outputs from the plurality of the photoelectrically converting means are respectively integrated so as to be detected as the distribution of light reflected by the plurality of the regions of the subject field due to the flash light. Information about the detected distribution of light reflected by the plurality of the regions of the subject field is arithmetically processed in accordance with a predetermined multipattern algorithm. As a result, the degree of weighting the plurality of the regions is determined so as to obtain the most suitable exposure for the essential subject. Subsequently, the flashing device is caused to intrinsically emit light immediately after the shutter has been opened. Light reflected from the surface of the film is, similarly to the above-described previous light emission, received by the plurality of the photoelectrically converting means. The outputs from the photoelectrically converting means are subject to the weighting operation the degree of which has been determined as described above before they are added and integrated. The result of the integration is subjected to a comparison with a predetermined value. As a result, timing at which the light emission operation performed by the flashing device is stopped is determined, the timing being used to determine the quantity of light emitted. The above-described TTL light controlling method, that is, the TTL light control system in which the pre-emission operation is performed is hereinafter called a "TTL multicontrol", while a TTL light control system in which no pre-emission operation is hereinafter called a "TTL normal light control".
When the TTL multicontrol structure disclosed in U.S. Ser. No. 560,745 is adapted to an actual camera system, both the camera body and the flashing device must have novel functions respectively. That is, the camera body must have a photoelectrically converting means capable of performing the partitive photometry and an output signal processing circuit, a sequence control means and the like. The flashing device must have a means capable of quickly repeating the pre-emission operation and the intrinsic emission operation and as well as controlling the quantity of light emitted in such a manner that the maximum quantity of light emitted at the pre-emission operation is restricted for the purpose of maintaining the quantity of light which can be emitted at the intrinsic emission operation. Furthermore, it is preferable that a common contact be used to pass both the emission start signals and the emission stop signals for use in the pre-emission operation and the intrinsic emission operation.
However, the camera body and the flashing device having the above-described functions can, in actuality, be coupled to conventional structures respectively. Therefore, it is necessary to satisfactorily realize the functions, which have heretofore been realized, in the above-described adaptation. For example, if the camera body having the novel functions and a conventional type flashing device are coupled to each other, the conventional TTL normal light control can be performed in response to the first light emission signal while neglecting the pre-emission operation. On the contrary, if the conventional type camera body and the flashing device having the novel functions are coupled to each other, the flashing device must not recognize the emission start signal which is transmitted in the shutter releasing operation, as the pre-emission light.